High-energy femtosecond laser pulse compression in single- and multi-ionization regime of rare gases: experiment versus theory
We report experimental and numerical results on the post-compression of 40 fs duration pulses down to 10 fs at high energy level (multi-mJ). The spectral broadening is achieved through the self-phase modulation resulting from optical-field-ionization of different noble gases (He, Ne, Ar) by the 40-fs laser pulse propagating in a low-pressure gas-filled hollow capillary. We discuss the influence of the multi-ionization dynamics, through the gas dependence, on the laser energy carried by the capillary, as well as on the duration and temporal shape of the post-compressed pulses. In all the different experimental conditions investigated in this article (pressures and gases used), the experimental data is in good agreement with the numerical results from a three-dimension propagation code. Through this study, we demonstrate the robustness of the proposed post-compression technique with regard to multi-ionization, indicating that it can be used on a large intensity range by judiciously choosing the gas.
KeywordsGroup Velocity Dispersion Spectral Phase Ionization Charge State Mbar Pressure Light Grey Line
The authors thank C. Medina, R. Bouillaud, and L. Merzeau for their technical assistance. This work is supported by the Conseil Regional d’Aquitaine (COLA2 2.1.3 09010502), the European Union (EU) (LaserLabII ALADIN) and the Agence Nationale de la Recherche (ANR-09- BLAN-0031-02).